Polyphenylene sulfide (“PPS”) is a high performance polymer that can withstand high thermal, chemical, and mechanical stresses. Due to its relatively slow crystallization rate, however, injection molding of parts from polyphenylene sulfide can be challenging. For example, to achieve the desired degree of crystallization, molding is generally conducted at a high mold temperature (˜130° C. or more) and for a relatively long cycle time. Unfortunately, high mold temperatures typically dictate the need for expensive and corrosive cooling mediums (e.g., oils) in order to achieve good mechanical properties. Attempts to address the problems noted above have generally involved the inclusion of various additives in the polymer composition to help improve its crystallization properties. To date, however, such attempts have not been fully satisfactory. As such, a need exists for a suitable method for injection molding polyarylene sulfide at low temperatures while still achieving good mechanical properties.